Combining hydroponic crop waste with algae treatment to lessen the effects of nutrient waste streams

Abstract

Globally, controlled environment agriculture (CEA) is growing, yet little is understood about nutrient losses in these systems or how to lessen pollution that results. This project explores the possibility of using algae to clean effluent from hydroponically grown vegetables.The 4-layer nutrition film technology (NFT) vertical farming rack produced 132 heads of lettuce in total. The hydroponic system's waste was used to grow naturally existing algae. At every step of manufacturing, measurements were made of nitrogen (N), phosphorus (P), and other trace elements (Ca, Co, Cu, Fe, K, Mg, Mn, Mo, Ni, and Zn).Findings: The applied mineral nitrogen (N) and phosphorus (P) had an overall nutrient utilization efficiency (NUE) of 88.7% and 59.4%, respectively. The complete system NUE of N and P was 99.5% and 95.0%, respectively, after algal treatment of waste streams, greatly lowering waste headed for sewage. Large amounts of Ca, Cu, Fe, and Zn from the rooting sponges employed in this experiment were discovered to be ingested by the crops; these elements may have been made accessible by mineralization and the presence of a somewhat acidic fertilizer solution. The rooting sponge's overall waste production, which accounts for around 53% and 6% of the system's total N and P intake, raises concerns about the system's overall NUE.Conclusions: This research shows that using algae to remediate wastewater streams from controlled environment agriculture (CEA) techniques, including hydroponics, is effective and requires minimal work. In order to enhance the environmental credentials of new CEA systems, further efforts by academics and the CEA industry to better regulate nutrient streams are advised.